I, for one, welcome our new fullscreen overlords

This raises two concerns: first and foremost, the ability for malicious developers to exploit the feature (specially for ads). This seems to be well addressed by way of the security features and rules that you have to follow when triggering the fullscreen mode. However, this raises my second concern: you can’t use keyboard events at all on fullscreen mode, making the feature useless for games that need keyboard control.

All in all, it’s a great feature, but it seems it was added just for YouTube and Google Video – so people can watch video in fullscreen without opening a new page.